If you take a pebble with a radius of about one centimeter and you throw it off a high building, it will reach a speed which will not exceed 75 miles per hour because of the air drag.
如果拿一个半径是，1厘米的小卵石，从高楼上扔下去，它的速度因为空气阻力，不过超过每小时75英里。
2
The vehicle must takeoff and land at an airport; once in the air, it can range 460 miles at a speed of 110 miles per hour.